There has been known a product including a tray-like container with a bottom covered with a liquid absorbent material, such as sand, as a pet toilet for disposing excretory liquid (urine) of a pet such as a cat or a dog. When a person cares for a cat by using such toilet, he/she needs to prevent scattering of sand, since a cat has a behavior of throwing sand on an excretion place after the excretion. For this purpose, a sidewall of a tray storing sand in the pet toilet has to be made high. For example, Patent Literature 1 describes an animal toilet including a rectangular granular matter storing container in plan view, wherein sidewalls are formed on three faces, and the remaining one face is formed low to set a gate. In this toilet, scattering of sand from the gate cannot be prevented. Therefore, in the Patent Literature 1, another member is arranged on the gate to prevent the scattering of sand. However, the arrangement of another member leads to an increase in the number of components of the toilet, and this is uneconomical. Since the position of the gate is high in the toilet described in the Patent Literature 1, the gate is higher than an eye line of a young small animal that is cared for, and the animal is difficult to recognize the position of the gate. Even if it can recognize the gate, the gate is too high, so that it cannot go in the toilet. The same applies to an animal having low physical performance due to old age or disease.
A toilet described in Patent Literature 2 has been known as a toilet that can be used for a cat that cannot go over a high sidewall due to decrease in physical performance. In this toilet, instead of forming a gate into a slope having a small height, and the slope with an opening from which sand can drop downward is formed. However, this slope is only used to keep a kitten or a cat having low physical performance, and it is unnecessary to keep a healthy mature cat. Accordingly, when a healthy mature cat is kept, the size of the toilet is increased by the size of the slope.